The Warming of Greenland

By JOHN COLLINS RUDOLF

Published: January 16, 2007

CORRECTION APPENDED

Flying over snow-capped peaks and into a thick fog, the helicopter set down on a barren strip of rocks between two glaciers. A dozen bags of supplies, a rifle and a can of cooking gas were tossed out onto the cold ground. Then, with engines whining, the helicopter lifted off, snow and fog swirling in the rotor wash.

When it had disappeared over the horizon, no sound remained but the howling of the Arctic wind.

''It feels a little like the days of the old explorers, doesn't it?'' Dennis Schmitt said.

Mr. Schmitt, a 60-year-old explorer from Berkeley, Calif., had just landed on a newly revealed island 400 miles north of the Arctic Circle in eastern Greenland. It was a moment of triumph: he had discovered the island on an ocean voyage in September 2005. Now, a year later, he and a small expedition team had returned to spend a week climbing peaks, crossing treacherous glaciers and documenting animal and plant life.

Despite its remote location, the island would almost certainly have been discovered, named and mapped almost a century ago when explorers like Jean-Baptiste Charcot and Philippe, Duke of Orl?s, charted these coastlines. Would have been discovered had it not been bound to the coast by glacial ice.

Maps of the region show a mountainous peninsula covered with glaciers. The island's distinct shape -- like a hand with three bony fingers pointing north -- looks like the end of the peninsula.

Now, where the maps showed only ice, a band of fast-flowing seawater ran between a newly exposed shoreline and the aquamarine-blue walls of a retreating ice shelf. The water was littered with dozens of icebergs, some as large as half an acre; every hour or so, several more tons of ice fractured off the shelf with a thunderous crack and an earth-shaking rumble.

All over Greenland and the Arctic, rising temperatures are not simply melting ice; they are changing the very geography of coastlines. Nunataks -- ''lonely mountains'' in Inuit -- that were encased in the margins of Greenland's ice sheet are being freed of their age-old bonds, exposing a new chain of islands, and a new opportunity for Arctic explorers to write their names on the landscape.

''We are already in a new era of geography,'' said the Arctic explorer Will Steger. ''This phenomenon -- of an island all of a sudden appearing out of nowhere and the ice melting around it -- is a real common phenomenon now.''

In August, Mr. Steger discovered his own new island off the coast of the Norwegian island of Svalbard, high in the polar basin. Glaciers that had surrounded it when his ship passed through only two years earlier were gone this year, leaving only a small island alone in the open ocean.

''We saw it ourselves up there, just how fast the ice is going,'' he said.

With 27,555 miles of coastline and thousands of fjords, inlets, bays and straits, Greenland has always been hard to map. Now its geography is becoming obsolete almost as soon as new maps are created.

Hans Jepsen is a cartographer at the Geological Survey of Denmark and Greenland, which produces topographical maps for mining and oil companies. (Greenland is a largely self-governing region of Denmark.) Last summer, he spotted several new islands in an area where a massive ice shelf had broken up. Mr. Jepsen was unaware of Mr. Schmitt's discovery, and an old aerial photograph in his files showed the peninsula intact.

''Clearly, the new island was detached from the mainland when the connecting glacier-bridge retreated southward,'' Mr. Jepsen said, adding that future maps would take note of the change.

The sudden appearance of the islands is a symptom of an ice sheet going into retreat, scientists say. Greenland is covered by 630,000 cubic miles of ice, enough water to raise global sea levels by 23 feet.

Carl Egede Boggild, a professor of snow-and-ice physics at the University Center of Svalbard, said Greenland could be losing more than 80 cubic miles of ice per year.

''That corresponds to three times the volume of all the glaciers in the Alps,'' Dr. Boggild said. ''If you lose that much volume you'd definitely see new islands appear.''

He discovered an island himself a year ago while flying over northwestern Greenland. ''Suddenly I saw an island with glacial ice on it,'' he said. ''I looked at the map and it should have been a nunatak, but the present ice margin was about 10 kilometers away. So I can say that within the last five years the ice margin had retreated at least 10 kilometers.''

The abrupt acceleration of melting in Greenland has taken climate scientists by surprise. Tidewater glaciers, which discharge ice into the oceans as they break up in the process called calving, have doubled and tripled in speed all over Greenland. Ice shelves are breaking up, and summertime ''glacial earthquakes'' have been detected within the ice sheet.

''The general thinking until very recently was that ice sheets don't react very quickly to climate,'' said Martin Truffer, a glaciologist at the University of Alaska at Fairbanks. ''But that thinking is changing right now, because we're seeing things that people have thought are impossible.''

A study in The Journal of Climate last June observed that Greenland had become the single largest contributor to global sea-level rise.

Correction: January 18, 2007, Thursday
Because of an editing error, an article in Science Times on Tuesday about the appearance of a new island as a result of glacial melting in Greenland referred incorrectly to a region where another such island has appeared. Svalbard, off Norway, is an archipelago, not an island.